The present invention relates to a hybrid scanning type ion implantation apparatus in which an ion beam is electrically scanned and a wafer is mechanically scanned in the direction substantially perpendicular to the scanning direction of ion beam, and method of controlling the same.
FIG. 1 shows a prior art of such a type of ion implantation apparatus.
With scanning means (not shown), an ion beam 2 is electrically scanned in the X direction (for example, in the horizontal direction). The ion beam may be arranged into a parallel beam by using an electric field or a magnetic field as shown in the drawing. The parallely arranged ion beam 2 is guided to an implantation chamber (not shown). A holder 1300 for holding a wafer 4 is disposed in the implantation chamber. The holder 1300 is mechanically scanned by a holder drive unit 1360 in the Y direction perpendicular to the X direction (for example, in the vertical direction).
The holder drive unit 1360 mainly comprises a holder raising unit 1320 for rotating the holder 1300 between a vertical position in which ions are implanted to the wafer 4 and a horizontal position in which the wafer 4 is handled and a holder lifting unit 1340 for lifting and lowering the holder 1300 along with the holder raising unit 1320 in the Y direction so as to mechanically scan the wafer 4.
However, according to the above described structure, the holder lifting unit 1340 is such that a rotation movement by a motor is converted into a linear movement by using, for example, worm gears, so that its stroke is long. Thus, if the entirety of these mechanisms is contained in the implantation chamber, a vacuum container becomes large and this type of apparatus becomes large.
On the other hand, if the motor is positioned in the atmosphere, a slide shaft moving linearly to lift and lower the holder 1300 goes in and out the implantation chamber of vacuum state and the atmosphere. Thus, it is necessary to design not to bring the air and the like into the implantation chamber through the linear movement of the slide shaft. For example, a dynamic vacuum seal system has been considered in which the slide shaft passing through the vacuum container is constructed to slide through a plurality of divided chambers at non-contact state and the respective chambers are differentially exhausted by respective vacuum pumps. However, the system is disadvantageous in that it is very complicated and exhausting the implantation chamber into high vacuum is difficult so that a high power vacuum pump must be used for the implantation chamber.